Chain grate stoker



Dec. 12, i933. w. M DUNCAN v 1,939,164

CHAIN GRATE STOKER Filed Dec. 28. 1931 o t oL o o o o Patented Dec. 12, 1933 f 1,939,164 e CHAIN GRATESTOKER William Dundee, Alton, n1; 5

Appucaeon Deeember 2s, 1931 Serial No. 583,571 y' eoia'ims. (ci. 11o- 4m- "This" inventionrelates to certain new and usefulimprovements 'inr chain fgratev stokers', the peculiarities of Vwhich-will behereinafter fully described and claimed.

` The main objectsof my invention are first, to improve the construction and operationpi my prior Patent No. 1,145,573; second, to provide a resilient seal for dempers; third,`to provide multiple dempers which are more easily operated in Vl0 opening and closing positions; fourth, to provide" endcl os ing walls forming la draft chamber of restrictedsize corresponding to the active grate surface'for regulating the air currents'entering said chamber andA more evenly disposing themv to the multiplel dempers `selectively delivering air to the activ?J grate surface; fifth, to `obstructthe passage of lair longitudinally under andthrough the strands 'of `stoker chains, and lsubstantially confine the upward draftto'the selected portions 201 of' grate surface above the open damper oridam'perssixth, tofprovideY temporary storage compartments above the dempers for the coal parfticles siftingthrougn the grate and collecting on the closed dempers; and seventh, to provide other features of ocnstruction'and operation hereinafter'described and claimed.

' tokersfequipped with dempers Vin accordance with my priorPatent' No. 1,145,573, have proved remarkably eicient in saving Yfuel by the elimination of excess air passing upwardly through the gr'ate, l: 1,1tl on account of the-'construction of those dempers a-perfect sealcould not b e main? tained, due to slight warping of the damper plate;l irregularities of contiguous castings, or slight 35.1neccuracies of workmanship. It has also been found that my prior form of center-pivoted dempers were often difficult to open, due to fine coal particles sifting through the grate and filling thespace between the closed damper and the 4() lower plane of the grate strands.

It is to the elimination of these objectionable features and the provision of improved construction and operation, that my present applicationr relates.

buildings-but on boilers supplying steam for power generation as well, the load is by no means. constant. To make the active grate surface com-V parable with the boiler load that is to be carried, cdampers or closures are provided by which air cen be excluded, limited, or freely admitted, selectively to various areas of the grate. To be fully eiective, especially when banking a fire, Y

(that is, maintaining a bed of glowing coal without producing steam in the boiler over a pro- Not only on boilers supplying steam for heating tracted period) -it is lessential thatV the dampers close 'so tightly thatno airthattendstoburn out the coal will v'pass by them. This desired effect; is obtainedby' the construction which is the -subject of my present application f Y'In the accompanying drawing'inwhich like reference numeralsindicate corresponding'part'sf Fig. 1 represents 'ailongitudinalfsectiongof a chain grate stoker on a verticalplaiie inside the stoker sides; f vr 651, VFig. 2, an enlarged sectional view of .the'darnper seals; and i f f` Fig. 3*, asimilarview'of a modification of the damper and seals.

Vlteferring to the drawing,'-the-numeral ldesig-i 70;,

nates the stoker drive shaft on which are mounted` sprockets V2 for imparting longitudinal travel V'toi chain links 3,--pivote'd` together in `longitudinal\ strands passing 'over-rear' drums 4"mountedon arear shaft 5; Thesefsprockets and drums sepa-W15' j rate ftheL strands into `upper andlowerv 'rows' of i traveling grate; A suitable Stoker hoppeizA 'de`v livers the coal to the upper row, Aand it 'isvcarried under: the front wallB of' theV furnace oto'feon-VVK stitute the fuel bed on the active.grate'surface.l 80r- I-beamsor other'forms of transverse bars 7, connect the Stoker sides ll yand supportilongie projectionsl such as at -15 extending in to the 90..

spaces between `the' strands and'forming baffles v on the links. Y 1

Directly under the Yseal bars 13 and preferably resting on the transverse supports?, are mount-v ed thin, resilient metal strips 12 extending be-' 95 tween the Stoker sides 11 and projecting laterv ally on each side beyond the supports 7 and seal bars 13. The projecting side edges of these resilient strips are preferably inclined downward `moreor less as shown in the figures, and form frames that define upward draft openings to the upper row and provide resilient edges for said seal bars 13. Y

In each of these openings are mounted one or more damper plates 8, each fastened near one side edge to rods 9 bymeans of lug castings l0for otherwise. The rodsv are os'cillatably-pivoted in suitable bearings in the stoker sides', and are mounted laterally beyond 'the adjacent resilient edge of the draft frame, so that the damper plate 1105 will engage and liex bothsaid resilient edges in moving to closing engagement with their underside, and substantially seal the draft' openingY Y vdamper is closed, will be discharged when the strands at the front and rear'endsof the activel grate surface, vertically disposed'plates Z2-22' 1 damper is inclined downward to Vopen position, and such opening is'readily eifected since all partsl of the loaded damper plate swing downward from its pivotal axis.

(In my prior patent above mentioned, thev packed coal deposit on the upper half of the c enter-pivoted damper was raised and pressed against the grate strands, thus obstructing operating the damper.)

ly more or less, according to theamount of-air it is desired to admit to the grate surface above the respective dampers. Any deposit of coal particles that may lodge on a slightly inclined damper may bedumped before closing ;.or theinclilld resilient edges will cut downthrough such depositwand eiect sealing engagement withV the` damper when raised to its closed position. In Fig. 3 these sealing edges are inclined more than in Figs, Vland-2, to accord with the normalV closedinclination ofthe double damper plates mounted inthe same draft opening. In this mcdication, the damper plates contact lwith the vre-` silient side-edges and also with eachI other in their inclined closing position, and'fform a hoppercorn-l partment adapted to store more sifted coal particles temporarily than the form shownin Figs.

Vl and 2. vEachof thedouble plates in Fig.j3 is pivotally mounted near its upper side edge, and 'Y the lower side edge of one plate member is b ent laterally as shown and forms a resilient side edge Y 12. for sealinglcontact with the-other plate member when its bent edge engages the lower plate,

in various upward adjustments of bothfplates. Pressure is exerted on the lower plateand positivesealing engagement between the two plates is obtained by a crank rod 20 and link 'connec-v `tion'21,y or other means.

. While I'have shown and' described .the inclined edge of the strip 12 as the resilient member-on' the draft frame,` the other damper member mayu have a, resilient edge as at 12.in Fig. 3, or otherwise,V but my preferredv form is that shown in Figs. 1 and 2. .l

Between .the upper and lower rows .of grate connect the stoker sides 11 and form with said their outer ends to the bottom of said draft chamber, connect the stoker sides and are'disposed substantially in contact with the under side of the lower row adjacent to said end closing plates. These plates extend toward each other and form a partial bottom forsaid chamber by obstructing the air draft between the links, of .the lower VArow near the end closingplates.

Above Vthese bottom plates, corresponding uplper plates 6-6 are. adjustably mounted substantially iii-contactk with the upper surface of the vlower row, and have vertical web portions My present dampers are opened independent-V posed between said bar and supportand Vproject-A ing laterallytherefrom, andan adjustable damper mountedbelow said plate andy yieldably contacting therewith in closedA position. 2,.l vAst oker,comprising an endless grate, transverse vseal vbars filling the vspace directly below the upper run of said grate and supportstherefor disposedat spaced intervals below said grate,

plates .interposed between said bars and sup.-V

portsi and having resilient edges projecting.V laterallyv therefrom on. each side,A and adjustable dampers mounted Lbelow saidplates andV making yieldable rcontact therewith in closed posit0I1-. Y. f .Y 3. A stokerA comprising anendless grate, transverse seal bars and supports therefor disposed atspaced intervals below the upper run of said' grate, plates interposed between said bars and supports and having `projecting resilient edges inclinedV downwardly on each side, and adjustable dampers mounted in said intervals andmaking yieldable Contact with said edges lwhen raised to closed position.

' f M. DUNCAN.

an endless grate,.a seal fis@ 

